Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes a sun gear member, a planet carrier member, and a ring gear member. The torque transmitting devices include clutches and brakes arranged within a transmission housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional application of U.S. patentapplication Ser. No. 11/746,396, filed May 9, 2007, which, in turn,claims the benefit of U.S. provisional patent application Ser. No.60/895,411, filed on Mar. 16, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of a pluralityof torque transmitting mechanisms, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member, aplurality of planetary gear sets, and a plurality of torque-transmittingmechanisms. The plurality of planetary gear sets each have a sun gearmember, a planetary carrier member, and a ring gear member.

In one aspect of the present invention, four of the gear sets are simpleplanetary gear sets.

In another aspect of the present invention, two of the plurality oftorque transmitting mechanisms are brakes.

In another aspect of the present invention, three of the torquetransmitting mechanisms are friction clutches.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1A is a schematic diagram of a transmission according to theprinciples of the present invention;

FIG. 1B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 1A;

FIG. 1C is a schematic diagram of another arrangement of thetransmission according to the principles of the present invention;

FIG. 1D is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 1C;

FIG. 2A is a schematic diagram of still another arrangement of thetransmission according to the principles of the present invention;

FIG. 2B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 2A;

FIG. 3A is a schematic diagram of still another arrangement of thetransmission according to the principles of the present invention;

FIG. 3B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 3A;

FIG. 4A is a schematic diagram of still another arrangement of thetransmission according to the principles of the present invention;

FIG. 4B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 4A;

FIG. 5A is a schematic diagram of still another arrangement of thetransmission according to the principles of the present invention;

FIG. 5B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 5A;

FIG. 6A is a schematic diagram of still another arrangement of thetransmission according to the principles of the present invention;

FIG. 6B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 6A;

FIG. 7A is a schematic diagram of still another arrangement of thetransmission according to the principles of the present invention; and

FIG. 7B is a chart showing feasible locations of the torque transmittingdevices for the arrangement of the transmission shown in FIG. 7A.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring now to FIG. 1A, an embodiment of a multi-speed or eight speedtransmission is generally indicated by reference number 10. Thetransmission 10 is illustrated as a rear-wheel drive or longitudinaltransmission, though various other types of transmission configurationsmay be employed. The transmission 10 includes a transmission housing 11,an input shaft or member 12, and an output shaft or member 14. The inputmember 12 is continuously connected to an engine (not shown) or to aturbine of a torque converter (not shown). The output member 14 iscontinuously connected with a final drive unit (not shown) or transfercase (not shown).

The transmission 10 includes a first planetary gear set 16, a secondplanetary gear set 18, a third planetary gear set 20, and a fourthplanetary gear set 22. The planetary gear sets 16, 18, 20 and 22 areconnected between the input member 12 and the output member 14. In apreferred embodiment of the present invention, the planetary gear set 16includes a sun gear member 24, a ring gear member 26, and a planetcarrier member 28 that rotatably supports a set of planet or piniongears 30 (only one of which is shown). The pinion gears 30 areconfigured to intermesh with the sun gear member 24 and the ring gearmember 26. The sun gear member 24 is connected for common rotation witha first shaft or intermediate member 32 and a second shaft orintermediate member 34. It should be appreciated that the firstintermediate member 32 is connected for common rotation with the secondintermediate member 34 and that the intermediate members 32 and 34 mayform one single shaft or multiple shafts through one or more members ofthe planetary gear sets, as seen throughout the several views. The ringgear member 26 is connected for common rotation with a third shaft orintermediate member 36. The planet carrier member 28 is connected forcommon rotation with a fourth shaft or intermediate member 38.

The planetary gear set 18 includes a sun gear member 42, a ring gearmember 44, and a planet carrier member 46 that rotatably supports a setof planet or pinion gears 48. The pinion gears 48 are configured tointermesh with the sun gear member 42 and the ring gear member 44. Thesun gear member 42 is connected for common rotation with the secondintermediate member 34. The ring gear member 44 is connected for commonrotation with a fifth shaft or intermediate member 50. The planetcarrier member 46 is connected for common rotation with the input member12.

The planetary gear set 20 includes a sun gear member 52, a ring gearmember 54, and a carrier member 56 that rotatably supports a set ofplanet or pinion gears 58. The pinion gears 58 are configured tointermesh with the sun gear member 52 and the ring gear member 54. Thesun gear member 52 is connected for common rotation with the fifth shaftor intermediate member 50 and with a sixth shaft or intermediate member51. It should be appreciated that the fifth intermediate member 50 isconnected for common rotation with the sixth intermediate member 51 andthat the intermediate members 50 and 51 may form one single shaft ormultiple shafts through one or more members of the planetary gear sets,as seen throughout the several views. The ring gear member 54 isconnected for common rotation with a seventh shaft or intermediatemember 60. The planet carrier member 56 is connected for common rotationwith an eighth shaft or intermediate member 62. It should be appreciatedthat the eighth intermediate member 62 is connected for common rotationwith the output member 14 and that the eighth intermediate members 62and the output member 14 may form one single shaft or multiple shaftsthrough one or more members of the planetary gear sets, as seenthroughout the several views.

The planetary gear set 22 includes a sun gear member 72, a ring gearmember 74, and a planet carrier member 76 that rotatably supports a setof planet or pinion gears 78. The pinion gears 78 are configured tointermesh with the sun gear member 72 and the ring gear member 74. Thesun gear member 72 is connected for common rotation with a ninth shaftor intermediate member 64 and a tenth shaft or intermediate member 66.It should be appreciated that the ninth intermediate member 64 isconnected for common rotation with the tenth intermediate member 66 andthat the intermediate members 64 and 66 may form one single shaft ormultiple shafts through one or more members of the planetary gear sets,as seen throughout the several views. The ring gear member 74 isconnected for common rotation with the fourth intermediate member 38.The planet carrier member 76 is connected for common rotation with theoutput member 14 and with the eighth intermediate member 62.

The transmission 10 includes a variety of torque-transmitting mechanismsor devices including a first intermediate clutch C1, a secondintermediate clutch C2, a third intermediate clutch C3, a first brake B1and a second brake B2. The first intermediate clutch C1 is selectivelyengagable to connect the input member 12 to the tenth intermediatemember 66. Alternatively, the first intermediate clutch C1 may beconnected to the input member 12 through the planet carrier member 46,as seen throughout the several views. The second intermediate clutch C2is selectively engagable to connect the sixth intermediate member 51 tothe ninth intermediate member 64. The third intermediate clutch C3 isselectively engagable to connect the seventh intermediate member 60 tothe ninth intermediate member 64. The brake B1 is selectively engagableto connect the first intermediate member 32 to the transmission housing11 to restrict rotation of the first intermediate member 32 relative tothe transmission housing 11. Finally, the brake B2 is selectivelyengagable to connect the third intermediate member 36 to thetransmission housing 11 to restrict rotation of the third intermediatemember 36 relative to the transmission housing 11.

The transmission 10 is capable of transmitting torque from the inputmember 12 to the output member 14 in at least eight forward torqueratios and one reverse torque ratio. Each of the forward torque ratiosand the reverse torque ratio are attained by engagement of one or moreof the torque-transmitting mechanisms (i.e. first intermediate clutchC1, second intermediate clutch C2, third intermediate clutch C3, brakeB1 and brake B2). Those skilled in the art will readily understand thata different speed ratio is associated with each torque ratio. Thus,eight forward speed ratios may be attained by the transmission 10.

The transmission housing 11 includes a first end wall 102, a second endwall 104, and a third wall 106. The third wall 106 interconnects betweenthe first and second end walls 102 and 104 to provide a space or cavity108 in which planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2 are located.Further, the cavity 108 has a plurality of areas or Zones A, B, C, D, E,and F in which the plurality of torque transmitting mechanisms C1, C2,C3, B1, and B2 will be specifically positioned, in accordance with thepreferred embodiments of the present invention.

As shown in FIG. 1A and throughout the several views, Zone A is definedby the area or space bounded: axially on the left by the first end wall102, on the right by planetary gear set 16, radially inward by areference line “L” which is a longitudinal line that is axially alignedwith the input shaft 12, and radially outward by a reference line “M”which is a longitudinal line that extends adjacent an outer diameter orouter periphery of the planetary gear sets 16, 18, 20, and 22. Whilereference line “M” is illustrated as a straight line throughout theseveral views, it should be appreciated that reference line “M” followsthe outer periphery of the planetary gear sets 16, 18, 20, and 22, andaccordingly may be stepped or non-linear depending on the location ofthe outer periphery of each of the planetary gear sets 16, 18, 20, and22. Zone B is defined by the area bounded: axially on the left byplanetary gear set 16, axially on the right by the planetary gear set18, radially outward by reference line “M”, and radially inward byreference line “L”. Zone C is defined by the area bounded: axially onthe left by the planetary gear set 18, axially on the right by theplanetary gear set 20, radially outward by reference line “M”, andradially inward by reference line “L”. Zone D is defined by the areabounded: axially on the left by the planetary gear set 20, axially onthe right by the planetary gear set 22, radially outward by referenceline “M”, and radially inward by reference line “L”. Zone E is definedby the area bounded: axially on the left by the planetary gear set 22,axially on the right by the second end wall 104, radially outward byreference line “M”, and radially inward by reference line “L”. Zone F isdefined by the area bounded: axially on the left by the first end wall102, axially on the right by the second end wall 104, radially inward byreference line “M” and radially outward by the third wall 106. As willbe described and illustrated hereinafter, planetary gear sets 16, 18,20, and 22 will change positions within the transmission cavity 108,however, the Zones described above will not change and will remain thesame as shown throughout the Figures.

In the arrangement of the transmission 10 shown in FIG. 1A, theplanetary gear sets 16, 18, 20, and 22 are longitudinally arranged inthe following order from left to right: 16-18-20-22. Specifically, theplanetary gear set 16 is disposed closest to the wall 102, the planetarygear set 22 is disposed closest to the wall 104, the planetary gear set18 is adjacent the planetary gear set 16, and the planetary gear set 20is disposed between the planetary gear sets 18 and 22. Thetorque-transmitting mechanisms are intentionally located within specificZones in order to provide advantages in overall transmission size,packaging efficiency, and reduced manufacturing complexity. In theparticular example shown in FIG. 1A, the torque-transmitting mechanismC1 is disposed within Zone C, the torque-transmitting mechanisms C2 andC3 are disposed within Zone D, and the torque-transmitting mechanisms B1and B2 are disposed within Zone F.

However, the present invention contemplates other embodiments where thetorque-transmitting mechanisms C1, C2, C3, B1, and B2 are disposed inthe other Zones. The feasible locations of the torque-transmittingdevices C1, C2, C3, B1, and B2 relative to the Zones are illustrated inthe chart shown in FIG. 1B. An “X” in the chart indicates that thepresent invention contemplates locating the particulartorque-transmitting device in any of the referenced Zones.

With reference to FIG. 1C, an alternate embodiment of the multi-speedtransmission is indicated by reference number 10B. The transmission 10Bincludes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation.

The transmission 10B includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged identically to the arrangement shown in FIG. 1A.However, in the particular example shown in FIG. 1C, thetorque-transmitting mechanisms C1 and C2 are disposed within Zone B. Asin the previous embodiment, the torque-transmitting mechanism C3 isdisposed within Zone D and the torque-transmitting mechanisms B1 and B2are disposed within Zone F.

Additionally, the present invention contemplates other embodiments oftransmission 10B where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 1D. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

Turning now to FIG. 2A, still another embodiment of the multi-speedtransmission is indicated by reference number 200. The transmission 200includes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation in FIG.2A.

The transmission 200 includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged in the following order from left to right:18-20-16-22. Specifically, the planetary gear set 18 is disposed closestto the wall 102, the planetary gear set 22 is disposed closest to thewall 104, the planetary gear set 20 is adjacent the planetary gear set18, and the planetary gear set 16 is disposed between the planetary gearsets 20 and 22. The torque-transmitting mechanisms are intentionallylocated within specific Zones in order to provide advantages in overalltransmission size, packaging efficiency, and reduced manufacturingcomplexity. In the particular example shown in FIG. 2A, thetorque-transmitting mechanisms C1 and C2 are disposed within Zone A, thetorque-transmitting mechanism C3 is disposed within Zone C, and thetorque-transmitting mechanisms B1 and B2 are disposed within Zone F.

However, the present invention contemplates other embodiments of thetransmission 200 where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 2B. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

With reference to FIG. 3A, still another embodiment of the multi-speedtransmission is indicated by reference number 300. The transmission 300includes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation in FIG.3A.

The transmission 300 includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged identically to the arrangement shown in FIG. 2A.However, the input shaft 12 is arranged such that it crosses theboundary between Zones A and F. In the particular example shown in FIG.3A, the torque-transmitting mechanisms C1 and C2 are disposed withinZone A, the torque-transmitting mechanism C3 is disposed within Zone C,and the torque-transmitting mechanisms B1 and B2 are disposed withinZone F.

However, the present invention contemplates other embodiments of thetransmission 300 where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 3B. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

With reference to FIG. 4A, still another embodiment of the multi-speedtransmission is indicated by reference number 400. The transmission 400includes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation in FIG.4A.

The transmission 400 includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged in the following order from left to right:18-16-20-22. Specifically, the planetary gear set 18 is disposed closestto the wall 102, the planetary gear set 22 is disposed closest to thewall 104, the planetary gear set 16 is adjacent the planetary gear set18, and the planetary gear set 20 is disposed between the planetary gearsets 16 and 22. The torque-transmitting mechanisms are intentionallylocated within specific Zones in order to provide advantages in overalltransmission size, packaging efficiency, and reduced manufacturingcomplexity. In the particular example shown in FIG. 4A, thetorque-transmitting mechanisms C1 and C2 are disposed within Zone A, thetorque-transmitting mechanism C3 is disposed within Zone C, and thetorque-transmitting mechanisms B1 and B2 are disposed within Zone F.

However, the present invention contemplates other embodiments of thetransmission 400 where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 4B. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

With reference to FIG. 5A, still another embodiment of the multi-speedtransmission is indicated by reference number 500. The transmission 500includes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation in FIG.5A.

The transmission 500 includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged in the following order from left to right:18-16-22-20. Specifically, the planetary gear set 18 is disposed closestto the wall 102, the planetary gear set 20 is disposed closest to thewall 104, the planetary gear set 16 is adjacent the planetary gear set18, and the planetary gear set 22 is disposed between the planetary gearsets 16 and 20. The torque-transmitting mechanisms are intentionallylocated within specific Zones in order to provide advantages in overalltransmission size, packaging efficiency, and reduced manufacturingcomplexity. In the particular example shown in FIG. 5A, thetorque-transmitting mechanisms C1 and C2 are disposed within Zone A, thetorque-transmitting mechanism C3 is disposed within Zone D, and thetorque-transmitting mechanisms B1 and B2 are disposed within Zone F.

However, the present invention contemplates other embodiments of thetransmission 500 where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 5B. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

With reference to FIG. 6A, still another embodiment of the multi-speedtransmission is indicated by reference number 600. The transmission 600includes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation in FIG.6A.

The transmission 600 includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged in the following order from left to right:20-18-16-22. Specifically, the planetary gear set 20 is disposed closestto the wall 102, the planetary gear set 22 is disposed closest to thewall 104, the planetary gear set 18 is adjacent the planetary gear set20, and the planetary gear set 16 is disposed between the planetary gearsets 18 and 22. The torque-transmitting mechanisms are intentionallylocated within specific Zones in order to provide advantages in overalltransmission size, packaging efficiency, and reduced manufacturingcomplexity. In the particular example shown in FIG. 6A, thetorque-transmitting mechanisms C1, C2, B1, and B2 are disposed withinZone F, and the torque-transmitting mechanism C3 is disposed within ZoneA.

However, the present invention contemplates other embodiments of thetransmission 600 where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 6B. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

With reference to FIG. 7A, still another embodiment of the multi-speedtransmission is indicated by reference number 700. The transmission 700includes the planetary gear sets 16, 18, 20, and 22 and thetorque-transmitting mechanisms C1, C2, C3, B1, and B2. The variouscomponents and connecting shafts that are identical with thetransmission 10 in FIG. 1A have the same numerical designation in FIG.7A.

The transmission 700 includes the planetary gear sets 16, 18, 20, and 22longitudinally arranged in the following order from left to right:20-22-18-16. Specifically, the planetary gear set 20 is disposed closestto the wall 102, the planetary gear set 16 is disposed closest to thewall 104, the planetary gear set 22 is adjacent the planetary gear set20, and the planetary gear set 18 is disposed between the planetary gearsets 22 and 16. The torque-transmitting mechanisms are intentionallylocated within specific Zones in order to provide advantages in overalltransmission size, packaging efficiency, and reduced manufacturingcomplexity. In the particular example shown in FIG. 7A, thetorque-transmitting mechanisms C1, C2, and C3 are disposed within ZoneB, the torque-transmitting mechanism B1 is disposed within Zone F, andthe torque-transmitting mechanism B2 is disposed within Zone E.

However, the present invention contemplates other embodiments of thetransmission 700 where the torque-transmitting mechanisms C1, C2, C3,B1, and B2 are disposed in the other Zones. The feasible locations ofthe torque-transmitting devices C1, C2, C3, B1, and B2 relative to theZones are illustrated in the chart shown in FIG. 7B. An “X” in the chartindicates that the present invention contemplates locating theparticular torque-transmitting device in any of the referenced Zones.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; atransmission housing having a first wall, a second wall, and a thirdwall extending between the first and second walls; a first, second,third and fourth planetary gear set disposed within the transmissionhousing, wherein the third planetary gear set is adjacent the firstwall, the fourth planetary gear set is adjacent the third planetary gearset, the first planetary gear set is adjacent the second wall, and thesecond planetary gear set is between the fourth and first planetary gearsets, each planetary gear set having a sun gear member, a ring gearmember, and a planet carrier member supporting a plurality of planetgears each configured to intermesh with both the sun gear member and thering gear member, wherein the input member is continuouslyinterconnected with the planet carrier member of the second planetarygear set, and the output member is continuously interconnected with theplanet carrier member of the fourth planetary gear set and the planetcarrier member of the third planetary gear set, and wherein the ringgear member of the fourth planetary gear set is permanently coupled tothe planet carrier member of the first planetary gear set; wherein thetransmission housing has a first area defined radially inward from anouter periphery of the planetary gear sets and axially bounded by thefirst wall and the third planetary gear set, a second area definedradially inward from the outer periphery of the planetary gear sets andaxially bounded by the third and fourth planetary gear sets, a thirdarea defined radially inward from the outer periphery of the planetarygear sets and axially bounded by the fourth and second planetary gearsets, a fourth area defined radially inward from the outer periphery ofthe planetary gear sets and axially bounded by the second and firstplanetary gear sets, a fifth area defined radially inward from the outerperiphery of the planetary gear sets and axially bounded by the firstplanetary gear set and the second wall, and a sixth area definedradially inward from the third wall and radially outward from the outerperiphery of the planetary gear sets and axially bounded by the firstwall and the second wall; a first clutch selectively engageable tointerconnect the sun gear member of the fourth planetary gear set to theplanet carrier member of the second planetary gear set; a second clutchselectively engageable to interconnect the sun gear member of the fourthplanetary gear set to the sun gear member of the third planetary gearset and the ring gear member of the second planetary gear set; a thirdclutch selectively engageable to interconnect the sun gear member of thefourth planetary gear set to the ring gear member of the third planetarygear set; a first brake selectively engageable to interconnect the sungear member of the first planetary gear set and the sun gear member ofthe second planetary gear set to the transmission housing; and a secondbrake selectively engageable to interconnect the ring gear member of thefirst planetary gear set to the transmission housing, wherein the firstclutch is located in at least one of the first, second, or sixth areas,the second clutch is located in at least one of the first, second, andsixth areas, the third clutch is located in at least one of the first,second, and sixth areas, the first brake is located in at least one ofthe first, fourth, fifth, and sixth areas, and the second brake islocated in at least one of the first, fifth, and sixth areas, andwherein the clutches and brakes are selectively engageable to establishat least eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 2. The transmission ofclaim 1 wherein the first clutch is located in the second area, thesecond clutch is located in the second area, the third clutch is locatedin the second area, the first brake is located in the sixth area, andthe second brake is located in the fifth area.
 3. The transmission ofclaim 1 wherein each of the first, second, third, fourth, and fifthareas are bounded axially by the outer peripheries of the first andsecond walls and the outer peripheries of the first, second, third, andfourth planetary gear sets.
 4. The transmission of claim 1 wherein thefirst clutch is located in the first area.
 5. The transmission of claim1 wherein the first clutch is located in the second area.
 6. Thetransmission of claim 1 wherein the first clutch is located in the sixtharea.
 7. The transmission of claim 1 wherein the second clutch islocated in the first area.
 8. The transmission of claim 1 wherein thesecond clutch is located in the second area.
 9. The transmission ofclaim 1 wherein the second clutch is located in the sixth area.
 10. Thetransmission of claim 1 wherein the third clutch is located in the firstarea.
 11. The transmission of claim 1 wherein the third clutch islocated in the second area.
 12. The transmission of claim 1 wherein thethird clutch is located in the sixth area.
 13. The transmission of claim1 wherein the first brake is located in the first area.
 14. Thetransmission of claim 1 wherein the first brake is located in the fourtharea.
 15. The transmission of claim 1 wherein the first brake is locatedin the fifth area.
 16. The transmission of claim 1 wherein the firstbrake is located in the sixth area.
 17. The transmission of claim 1wherein the second brake is located in the first area.
 18. Thetransmission of claim 1 wherein the second brake is located in the fiftharea.
 19. The transmission of claim 1 wherein the second brake islocated in the sixth area.
 20. A transmission comprising: an inputmember; an output member; a transmission housing having a first wall, asecond wall, and a third wall extending between the first and secondwalls; a first, second, third and fourth planetary gear set disposedwithin the transmission housing, wherein the third planetary gear set isadjacent the first wall, the fourth planetary gear set is adjacent thethird planetary gear set, the first planetary gear set is adjacent thesecond wall, and the second planetary gear set is between the fourth andfirst planetary gear sets, each planetary gear set having a sun gearmember, a ring gear member, and a planet carrier member supporting aplurality of planet gears each configured to intermesh with both the sungear member and the ring gear member, wherein the input member iscontinuously interconnected with the planet carrier member of the secondplanetary gear set, and the output member is continuously interconnectedwith the planet carrier member of the fourth planetary gear set and theplanet carrier member of the third planetary gear set, and wherein thering gear member of the fourth planetary gear set is permanently coupledto the planet carrier member of the first planetary gear set; whereinthe transmission housing has a first area defined radially inward froman outer periphery of the planetary gear sets and axially bounded by thefirst wall and the third planetary gear set, a second area definedradially inward from the outer periphery of the planetary gear sets andaxially bounded by the third and fourth planetary gear sets, a thirdarea defined radially inward from the outer periphery of the planetarygear sets and axially bounded by the fourth and second planetary gearsets, a fourth area defined radially inward from the outer periphery ofthe planetary gear sets and axially bounded by the second and firstplanetary gear sets, a fifth area defined radially inward from the outerperiphery of the planetary gear sets and axially bounded by the firstplanetary gear set and the second wall, and a sixth area definedradially inward from the third wall and radially outward from the outerperiphery of the planetary gear sets and axially bounded by the firstwall and the second wall; a first clutch selectively engageable tointerconnect the sun gear member of the fourth planetary gear set to theplanet carrier member of the second planetary gear set; a second clutchselectively engageable to interconnect the sun gear member of the fourthplanetary gear set to the sun gear member of the third planetary gearset and the ring gear member of the second planetary gear set; a thirdclutch selectively engageable to interconnect the sun gear member of thefourth planetary gear set to the ring gear member of the third planetarygear set; a first brake selectively engageable to interconnect the sungear member of the first planetary gear set and the sun gear member ofthe second planetary gear set to the transmission housing; and a secondbrake selectively engageable to interconnect the ring gear member of thefirst planetary gear set to the transmission housing, wherein the firstclutch is located in at least one of the first, second, or sixth areaswhen the second clutch is located in the second area, the third clutchis located in the second area, the first brake is located in the sixtharea, and the second brake is located in the fifth area, wherein thesecond clutch is located in at least one of the first, second, and sixthareas when the first clutch is located in the second area, the thirdclutch is located in the second area, the first brake is located in thesixth area, and the second brake is located in the fifth area, whereinthe third clutch is located in at least one of the first, second, andsixth areas when the first clutch is located in the second area, thesecond clutch is located in the second area, the first brake is locatedin the sixth area, and the second brake is located in the fifth area,wherein the first brake is located in at least one of the first, fourth,fifth, and sixth areas when the first clutch is located in the secondarea, the second clutch is located in the second area, the third clutchis located in the second area, and the second brake is located in thefifth area, wherein the second brake is located in at least one of thefirst, fifth, and sixth areas when the first clutch is located in thesecond area, the second clutch is located in the second area, the thirdclutch is located in the second area, and the first brake is located inthe sixth area, and wherein the clutches and brakes are selectivelyengageable to establish at least eight forward speed ratios and at leastone reverse speed ratio between the input member and the output member.21. The transmission of claim 20 wherein each of the first, second,third, fourth, and fifth areas are bounded axially by the outerperipheries of the first and second walls and the outer peripheries ofthe first, second, third, and fourth planetary gear sets.
 22. Atransmission comprising: an input member; an output member; atransmission housing having a first wall, a second wall, and a thirdwall extending between the first and second walls; a first, second,third and fourth planetary gear set disposed within the transmissionhousing, wherein the third planetary gear set is adjacent the firstwall, the fourth planetary gear set is adjacent the third planetary gearset, the first planetary gear set is adjacent the second wall, and thesecond planetary gear set is between the fourth and first planetary gearsets, each planetary gear set having a sun gear member, a ring gearmember, and a planet carrier member supporting a plurality of planetgears each configured to intermesh with both the sun gear member and thering gear member, wherein the input member is continuouslyinterconnected with the planet carrier member of the second planetarygear set, and the output member is continuously interconnected with theplanet carrier member of the fourth planetary gear set and the planetcarrier member of the third planetary gear set, and wherein the ringgear member of the fourth planetary gear set is permanently coupled tothe planet carrier member of the first planetary gear set; wherein thetransmission housing has a first area defined radially inward from anouter periphery of the planetary gear sets and axially bounded by thefirst wall and the third planetary gear set, a second area definedradially inward from the outer periphery of the planetary gear sets andaxially bounded by the third and fourth planetary gear sets, a thirdarea defined radially inward from the outer periphery of the planetarygear sets and axially bounded by the fourth and second planetary gearsets, a fourth area defined radially inward from the outer periphery ofthe planetary gear sets and axially bounded by the second and firstplanetary gear sets, a fifth area defined radially inward from the outerperiphery of the planetary gear sets and axially bounded by the firstplanetary gear set and the second wall, and a sixth area definedradially inward from the third wall and radially outward from the outerperiphery of the planetary gear sets and axially bounded by the firstwall and the second wall; a first clutch selectively engageable tointerconnect the sun gear member of the fourth planetary gear set to theplanet carrier member of the second planetary gear set; a second clutchselectively engageable to interconnect the sun gear member of the fourthplanetary gear set to the sun gear member of the third planetary gearset and the ring gear member of the second planetary gear set; a thirdclutch selectively engageable to interconnect the sun gear member of thefourth planetary gear set to the ring gear member of the third planetarygear set; a first brake selectively engageable to interconnect the sungear member of the first planetary gear set and the sun gear member ofthe second planetary gear set to the transmission housing; and a secondbrake selectively engageable to interconnect the ring gear member of thefirst planetary gear set to the transmission housing, wherein the firstclutch is located in the second area, the second clutch is located inthe second area, the third clutch is located in the second area, thefirst brake is located in the sixth area, and the second brake islocated in the fifth area, and wherein the clutches and brakes areselectively engageable to establish at least eight forward speed ratiosand at least one reverse speed ratio between the input member and theoutput member.